This invention generally relates to a hinge, and more particularly, to a hinge, which provides braking force against pivoting at all times.
A hinge of this type is used for mounting a flap body such as a liquid crystal display to the body of a device such as a laptop personal computer (a notebook personal computer) and a desktop personal computer equipped with a liquid crystal display, for instance. Braking action of the hinge permits the flap body mounted with the hinge of this type to maintain the state of inclination at a desired angle to the body of the device.
A description will now be given of the hinge of this type in the prior art with reference to FIGS. 7 and 8.
FIG. 7 is an exploded sectional view showing a hinge in the prior art, and FIG. 8 is a sectional view taken along line Cxe2x80x94C indicated by arrows in FIG. 7.
As shown in FIG. 7, a hinge 4a is composed of a cylindrical holding body 4 having a circular section hollow part 40 open to one end side and provided with a mounting part 41 on the other axial end side of the hollow part 40, and a shaft body 5 having a cylindrical part 50 open to one end side and provided with a mounting part 51 on the other axial end side of the cylindrical part 50.
Each of the mounting parts 41, 51 is adapted as a means of mounting the cylindrical holding body 4 and the shaft body 5 to a device, and an appropriate number of mounting holes 42, 52 are provided in the mounting parts 41, 51, respectively.
A small bore portion 40a, slightly smaller in diameter than the remainder of hollow 40, is formed at the inner bottom part of the hollow 40 in the cylindrical holding body 4. A pair of slots 50a, 50a is formed on the open side of the cylindrical part 50 of the shaft body 5. A portion of the cylindrical part 50 where the slots 50a, 50a are formed is press-fitted in the small bore part 40a of the hollow part 40 in the cylindrical holding body 4.
Since the material of the shaft body 5 is steel or the like subjected to carbonitriding, for instance, and the cylindrical part 50 of the shaft body 5 is provided with the slots 50a for elasticity, the cylindrical holding body 4 and the shaft body 5 are braked in the pivotal direction by the elastic action of the cylindrical part 50.
By selection of material for the shaft body 5, as well as by selection of size for the portion of the cylindrical part 50 where the slots 50a are formed, an elastic force, increasing in the circumferential direction, acts as a braking force against pivoting motion where the cylindrical part 50 is press-fitted in the hollow part 40.
The hinge 4a is used for mounting a flap body 61, serving as a display, on the body 60 of a device 6 such as a notebook personal computer, for example as shown in FIG. 9. In mounting the flap body 61 on the body 60, one of the mounting parts 41, 51 is fixed to the body 60, while the other is fixed to the flap body 61 with screws or the like (not shown).
As described above, the hinge exerts a specified braking force on the pivoting motion between cylindrical holding body 4 and the shaft body 5. Thus, when raising the flap body 61 to a desired angle, the braking force exceeds the weight of the flap body 61 in the closing direction and, as a result, the flap body 61 maintains its raised position without falling down.
Since the hinge in the prior art is structured so that the elastic force at the tip part of the cylindrical part 50 in the shaft body 5 applies a specified braking force on the portion where the cylindrical part 50 is press-fitted in the hollow part 40 as described the above, and the cylindrical part 50 of the shaft body 5 also exerts a braking force. However, frequent operation of the flap body 61 causes an age-based reduction in elastic force of the cylindrical part 50, resulting in a reduction in the braking force, shortening the life of the hinge.
Further, since the weight of the flap body normally varies according to the types of device, there is a need for manufacture of a different shaft body 5 for every different type of device, resulting in higher hinge manufacture cost. Furthermore, while the selection of material for the shaft body 5 and of size for the cylindrical part 50 permit adjustment of the circumferential elastic force at the tip of the cylindrical part 50 in the shaft body 5, it is difficult to adjust the braking force to meet required limits for the reason that the cylindrical part of the shaft body 5 is also used to exert the elastic force required for braking action. Thus, a hinge exerting an excessive braking force is in use in most cases.
Accordingly, it is an object of the present invention to provide a hinge providing a braking force against pivotal motion at all times, wherein an age-based reduction in braking force due to the frequent use of a flap body is prevented, thereby ensuring long life.
Another object of the present invention is to provide a hinge which makes it possible to use a common shaft body for different types of devices with various flap body weights, resulting in a reduction in manufacture cost.
A further object of the present invention is to provide a hinge which permits easy adjustment of braking force to meet required limits in a connecting part between a cylindrical holding body and a cylindrical part of a shaft body.
In a first embodiment of the present invention the hinge comprises a cylindrical holding body 1 having a circular section hollow part 10 and provided with a mounting part 11, a shaft body 2 having, at its tip, a cylindrical part 20 in which at least one axially extending slot 20a is formed and provided with a mounting part 21 at a base end side of the cylindrical part 20, and a spring 3 press-fitted into the cylindrical part 20 at the portion where the slot 20a is formed. The portion of the cylindrical part 20 with the slot 20a is press-fitted in the hollow part 10 of the cylindrical holding body 1.
A hinge in a second embodiment of the present invention is characterized in that the interior of the hollow part 10 of the cylindrical holding body 1 according to the first embodiment is modified by provision of a small bore 10a slightly smaller in diameter than the remaining portion of the hollow 10, and the portion of the cylindrical part 20 with slot 20a is press-fitted in small bore portion 10a. 
A hinge in a third embodiment of the present invention is characterized in that the spring 3 in the hinge of the first or second embodiment is modified to include a circular-arc section spring pin having a slit 30 extending along the longitudinal direction.
A hinge in a fourth embodiment of the present invention is characterized in that the spring 3 of the hinge according of the third embodiment is press-fitted in the hollow part 10 of the cylindrical holding body 1 such that the slit-shaped part 30 of the spring 3 is circumferentially aligned with the slot 20a of the cylindrical part 20. Preferably, the hinge according to each of the above embodiments has a pin 23 inserted in the base end side of the cylindrical part 20 of the shaft body 2, and also a slot 10b of a predetermined circumferential length in the hollow part 10 of the cylindrical holding body 1 serving to guide pin 23. Preferably, the hinge also has a solid part 20b on the base end side of the cylindrical part 20, and the pin 23 is a spring pin inserted into the solid part 20b.